Polymeric materials and additives therefor

ABSTRACT

A polymer additive for improving the reheat characteristics of a polymer or polymeric composition comprises an inorganic material which is such that a 2.5 mm thick polyethylene terephthalate plaque incorporating the inorganic material has, when tested, an absorption ratio of less than 0.9, wherein the absorption ratio is either the ratio of A1/A2 or the ratio A1/A3, wherein:
         A1 is the maximum absorption between 400 nm and 550 nm;   A2 is the maximum absorption between 700 to 1100 nm;   A3 is the maximum absorption between 700 to 1600 nm.       

     Preferred inorganic materials are titanium nitride, indium tin oxide and lanthanum hexaboride.

This application claims priority from U.S. patent application Ser No.10/599,403, filed Dec. 21, 2006 now U.S. Pat. No. 7,820,781, whichclaims the benefit of International Application No. PCT/GB2005/001231,which was published in English on Oct. 13, 2005, the disclosures ofwhich are incorporated herein by reference.

The present invention relates to polymeric materials and additivestherefor and particularly, although not exclusively, relates to polymercompositions having improved reheat properties, the use of suchcompositions, and to a method of production thereof. The invention alsoconcerns a polymer reheat additive which can be used with polymers andwhich may be useful when applied to thermoplastic polymers, especiallythose used in the field of container manufacturing.

Polymers are often used in producing preforms (parisons) which areheated with infrared heating lamps prior to being blow-molded intoarticles, including liquid containers such as beverage bottles and thelike. The heat lamps used for reheating polymer preforms (parisons) forthe commercial manufacture of liquid containers such as beverage bottlesare typically quartz lamps having a broad light emission spectrum from500 nm to greater than 1500 nm, i.e. infrared heating lamps. Polyester,especially polyethylene terephthalate (“PET”), absorbs poorly in theregion between 500 to 1400 nm. Thus, in order to speed up the reheatstep in bottle production, or to reduce the amount of energy requiredfor reheat, agents which absorb light in the region between 700 to 1300nm can be added to the polyester polymer as reheat additives.

A variety of black and grey body absorbing compounds have previouslybeen used as reheat additives to improve the rate of heatingcharacteristics of polyester under infrared heating lamps. Thesecompounds are typically black iron oxide, elemental antimony, blackcarbon and copper chromite. The term ‘black carbon’ includes graphite,any form of carbon black, charcoal, activated carbon and the like.However, these materials are inefficient in the forms in which they havebeen used and high levels of reheat cannot generally be achieved usingthe materials without the severe darkening of the polymer. Therefore,the amount of absorbing materials which can be added to a polymer islimited by the impact of those materials on polymer visual properties,such as transparency. This is particularly pertinent if the preforms areto be used to manufacture liquid containers such as beverage bottles,especially for use in containing mineral water, where high transparencyand an absence of color are considered essential. Transparency isusually represented as “L*” in the CIELAB system, with 100 being thehighest and 0 being the darkest. Generally, darker colored reheatadditives can be added in only very small quantities because of theirnegative impact on L*.

It is an object of the present invention to address the abovedescribedproblems

According to a first aspect of the invention, there is provided acomposition for improving the reheat characteristics of a polymericmaterial, the composition comprising an inorganic material.

According to a second aspect of the invention, there is provided acomposition comprising:

-   -   a polymeric material;    -   an inorganic material for improving the reheat characteristics        of the polymeric material, wherein the inorganic material is        such that a 2.5 mm thick polyethylene terephthalate plaque        incorporating the inorganic material has, when tested, an        absorption ratio of less than 0.9, wherein the absorption ratio        is either the ratio of A1/A2 or the ratio A1/A3, wherein:        -   A1 is the maximum absorption between 400 nm and 550 nm;        -   A2 is the maximum absorption between 700 to 1100 nm;        -   A3 is the maximum absorption between 700 to 1600 nm.

Preparation of the 2.5 mm thick plaque for testing inorganic materialsand tests may be as described in (A) or (B) below:

-   -   (A) An inorganic material to be tested is thoroughly mixed with        dried polymer pellets of a bottle grade PET having an IV of        0.8+/−0.02 and principal monomers pure terephthalic acid and        ethylene glycol. An example of such a material is VORIDIAN 9921        referred to hereinafter. Then the mixture is used to prepare 2.5        mm thick plaques using an injection molding machine. Further        details on procedure are provided in Examples 22 to 24        hereinafter.    -   (B) An inorganic aterial to be tested is added to monomers (e.g.        principal monomers pure terephthalic acid and ethylene glycol        arranged to produce the aforementioned PET) and the monomers are        polymerized. A plaque may subsequently be produced from the        polymer prepared as described in (A).

The preferred test is as described in (A).

The ability of an inorganic material to satisfy the requirements of theinvention of the second aspect may depend on the chemical identity ofthe inorganic material and may depend on physical features of theinorganic material such as particle sizes and shapes. In one case, oneparticular chemical type of inorganic material at a first particle sizemay not satisfy the test set forth according to the second aspect;however the same chemical type may at a second particle size (which maybe smaller than the first particle size) satisfy the test described andmay therefore be a useful material for incorporation into a polymericmaterial to improve the reheat characteristics of the polymericmaterial.

Suitably, the absorption ratio is less than 0.85. Preferably, the ratiois less than 0.80 and more preferably is less than 0.75.

Suitably, for a selected inorganic material, at least one (preferablyboth) of the following applies: the absorption ratio A1/A2 is less than0.70; and/or the absorption ratio A1/A3 is less than 0.90.

Preferably, for a selected inorganic material, at least one (preferablyboth) of the following applies: the absorption ratio A1/A2 is less than0.65; and/or the absorption ratio A1/A3 is less than 0.85.

More preferably, for a selected inorganic material, at least one(preferably both) of the following applies: the absorption ratio A1/A2is less than 0.60; and/or the absorption ratio A1/A3 is less than 0.80.

In an especially preferred embodiment, for a selected inorganicmaterial, at least one (preferably both) of the following applies: theabsorption ratio A1/A2 is less than 0.50; and/or the absorption ratioA1/A3 is less than 0.80.

Suitably, a selected inorganic material has an absorption ratio of A1/A2of less than 0.80, preferably less than 0.70, more preferably less than0.60, especially less than 0.56.

The absorption ratios A1/A2 and A1/A3 may each be greater than 0.2.

According to a third aspect of the invention, there is provided the useof an inorganic material as described according to the first or secondaspects for improving the reheat characteristics of a polymericmaterial.

According to a fourth aspect of the invention, there is provided aconcentrated formulation for addition to a polymeric material or to oneor more monomers arranged to be polymerized to prepare a polymericmaterial, said formulation comprising a carrier and an inorganicmaterial as described according to the first or second aspects.

The formulation may include a carrier which is a solid at standardtemperature and pressure (STP) or may comprise a liquid carrier. Whenthe carrier is a solid, the formulation is suitably a masterbatch. Whenthe carrier is a liquid, the inorganic material may be dissolved or,more preferably, dispersed in the liquid.

Preferably, the formulation includes less than 90 wt % of inorganicmaterials which are as described according to the first or secondaspects. Preferably, the sum of the wt % of all inorganic materials inthe formulation is less than 90 wt %, more preferably less than 75 wt %,especially less than 40 wt %. Preferably, the sum of the wt % of allparticulate material (including said inorganic materials) in saidformulation is less than 90 wt %, ore preferably less than 75 wt %,especially less than 40 wt %. Said formulation preferably includes atleast 0.0005 wt %, preferably at least 0.001 wt %, of inorganicmaterials which are as described according to the first or secondaspects.

When said concentrated formulation comprises a solid masterbatch, thesum of the wt % of inorganic materials which are as described accordingto the first or second aspects may be up to 90 wt %, up to 50 wt % or upto 40 wt %.

When said concentrated formulation comprises a liquid, for example aliquid dispersion comprising said inorganic material, the sum of the wt% of inorganic materials which are as described according to the firstor second aspects may be up to 90 wt %, up to 50 wt % or up to 40 wt %.

A liquid carrier may be a vegetable or mineral oil or a glycol. Aparticularly preferred glycol is ethylene glycol, especially if theparticles of inorganic material are to be added to a PET polymerizationreaction mixture. It may also be advantageous if the inorganic materialis milled in the liquid carrier. Milling serves to break down anyagglomerates present into primary particles.

Other components such as surfactants, thickening and stabilizing agentsmay be added to improve dispersion in the liquid carrier.

Other polymer additives may also be included in a liquid carrier such asslip property modifiers, acetaldehyde removing agents, IV modifiers,barrier agents such as Amosorb®, flame retardancy agents, surface finishmodifiers, conductivity modifiers and colors.

According to a fifth aspect of the invention, there is provided a methodof improving the reheat characteristics of a polymeric material, themethod comprising contacting the polymeric material or contacting one ormore monomers arranged to be polymerized to prepare the polymericmaterial with an inorganic aterial as described according to the firstor second aspects or otherwise as described herein.

The polymeric material or said monomers may be contacted with a powderwhich comprises or consists essentially of said inorganic material; ormay be contacted with a concentrated formulation as described accordingto the fourth aspect.

Whichever method is used to contact said polymeric material and saidinorganic material, it is preferred that sufficient of said inorganicmaterial is added so that at least 0.01 ppm, suitably at least 0.1 ppm,preferably at least 1 ppm, more preferably at least 2 ppm, even morepreferably at least 3 ppm, especially at least 4 ppm, based on theweight of said polymeric material, is present in the polymeric materialcontacted with inorganic material or is present in a polymeric materialpreparable from monomers arranged to be polymerized to prepare saidpolymeric material. Suitably, less than 1000 ppm, preferably less than500 ppm of said inorganic material is present in said polymericmaterial.

The ratio of the weight of polymeric material (or the weight of monomersarranged to be polymerized to prepare the polymeric material) to theweight of said inorganic material which contacts said polymeric material(or monomers) is suitably in the range 10³ to 10⁶, preferably in therange 2×10³ to 2.5×10⁵.

Contacting one or more monomers with an inorganic material as describedmay be a convenient way of incorporating the inorganic material, sinceit may then be easily mixed into the monomers and/or polymer indownstream steps for reacting/processing the monomers and/or thepolymer. Suitably, the inorganic material is incorporated into analcohol-group containing monomer stream if the polymeric material is aPET.

The method of the fifth aspect may include making granules or pelletswhich comprise the polymeric material and inorganic material.

According to a sixth aspect of the invention, there is provided apolymer reheat additive comprising an inorganic material having greaterintrinsic absorptivity in the infra-red region of the spectrum (between700 and 1400 nm) than in the visible region of the light spectrum(between 400 and 700 nm).

According to a seventh aspect of the invention there is provided apolymer reheat additive comprising an inorganic material having at leastone absorption maximum in the infra red region of the spectrum (between700 and 1400 nm) which is greater than any absorption maximum in thevisible region of the spectrum (between 400 and 700 nm).

The invention also provides a thermoplastic molding compositioncomprising a reheat additive as described herein. Also provided inaccordance with the invention is a molded article formed from such amolding composition. molding may be undertaken by thermoforming orinjection molding.

In one embodiment, the inorganic material may be a material other thanany form of black carbon, metallic antimony, iron oxide or copperchromite.

It has been discovered that certain inorganic materials can be useful inreheat applications. Particular inorganic materials and certain of theirphysical and/or chemical characteristics are described herein.Preferably, the inorganic materials absorb light in the infra redregion, are compatible with thermoplastic molding compositions, arenon-toxic and have an aesthetically neutral or positive impact on thecolor of a molded article formed from a composition to which they areadded.

According to an eighth aspect of the invention, there is provided athermoplastic molding composition comprising a polyester, and at leastone reheat additive comprising an inorganic material other than any formof black carbon, metallic antimony, iron oxide or copper chromite, thereheat additive being present in the composition in an amount effectiveto absorb light in the infra red region and thus reduce the energyrequirement for reheating to a blow molding temperature an articlemolded from the composition.

Additives and/or a selected inorganic materials described herein mayallow a polymer to have an improved reheat characteristic, wherein thepolymer reheats and therefore attains a temperature above its glasstransition temperature quicker and, consequently, reheat times may bereduced and productivity increased. The additives described maytherefore allow for more efficient handling of the polymer.

The polymer may comprise polymer particles, with the additive dispersedthroughout the polymer particles. Alternatively, the polymer may be asolid or fragmented with the additive disposed within the polymer. Theadditive may comprise colloids or particles, but will preferablycomprise nanoparticles. Nanoparticles may comprise particles with anaverage particle diameter less than 1 micron, preferably less than 100nm.

Inorganic materials referred to herein may be stoichiometric ornon-stoichiometric (when such forms can exist); non stoichiometric formsmay be preferred.

One class of inorganic materials (referred to herein as Type 1) whichmay be used for improving the reheat characteristics may comprisematerials which intrinsically exhibit greater absorptivity between 700and 1400 nm than between 400 and 700 nm. Absorptivity may be calculatedby measuring the absorbance of a polyester plaque containing thematerial at 400, 700 and 1100 nm and then determining the percentagechange in absorption that occurs between 400 and 700 nm and then 700 to1100 nm. Plaques incorporating preferred inorganic materials have a %absorptivity in the region 700 to 1100 nm which is greater than the %absorptivity in the region 400 to 700 nm and is positive in value. Aparticularly preferred example of such an inorganic material is reducedindium tin oxide. Intrinsic absorptivity, as used herein may be taken tobe the absorbance exhibited by a particle of the said material when theparticle size is sufficiently small that a significant amount of theimpinging light is transmitted at every wavelength.

A second class of inorganic materials (referred to herein as Type 2)which may be used for improving the reheat characteristics may comprisematerials which have a greater absorption maximum in the region between700 to 1400 nm than the average absorption between 400 and 700 nm. Theabsorption can be that directly measured by a spectrophotometer. Aparticularly preferred example of such an inorganic material is titaniumnitride.

Preferably, the additive and/or an inorganic material described hereinmay be capable of increasing energy absorption of a polymeric materialin the near-infra red light range (700 to approximately at least 1400nm). More preferably, the additive and/or a selected inorganic materialmay be capable of increasing energy absorption of the polymer in thenear-infra red light range more than it does in the visible light range(400 and 700 nm). Preferably, the selected inorganic material exhibits agreater absorptivity in the region between 700 and 1400 nm than between400 and 700 nm of at least 10%, more preferably at least 25%, and muchmore preferably at least 50% and yet more preferably still at least100%.

It is preferred that the additive and/or a selected inorganic materialhas an average energy absorption maximum in the range of 700 to 1400 nmwhich is greater than the average energy absorption in the range of 400and 700 nm. Suitably, the average energy absorption maximum in theregion between 700 to 1400 nm which is greater than the averageabsorption in the region between 400 to 700 nm is at least 1% greater,preferably is at least 5% greater and more preferably is at least 10%greater. It is most preferable that the average absorption maximum is atleast 50% greater.

If particles of an inorganic material selected as described herein aretoo large, they may absorb all of the impinging light in both thevisible and infrared portions of the spectrum, and may therefore provideno preferential absorption of infrared radiation. As the particle sizeis reduced, the relative absorption difference between the visible andinfrared portions of the spectrum may increase until the intrinsicabsorptivity is achieved. Hence, selection of the preferred particlesize for a said inorganic material may be dependent on the specificabsorptivity of an inorganic material in the visible and infraredportions of the electromagnetic spectrum.

The average (suitably the number average) particle size of additiveand/or selected inorganic material which may be used to increase theabsorption of energy between 700 and 1400 nm may be less than 10microns, preferably less than 1 micron and more preferably less than 100nm.

Suitably at least 90%, (preferably at least 95%, more preferably atleast 99%, especially about 100%) of the particles of said additiveand/or inorganic material have a maximum dimension which is less than 10microns, preferably less than 1 micron, more preferably less than 500nm, especially less than 100 nm.

In one embodiment, the inorganic material may be of such a particle sizethat, when incorporated into a polymeric material, it is substantiallyoptically invisible. For example, substantially all of the particles ofthe inorganic material may have a particle size which is below thecritical wavelength of visible light.

In one embodiment, the additive and/or selected inorganic material mayhave even or flat absorption characteristics across the visible regionof the spectrum with negligible absorption minima and maxima. This maybe desirable if a neutral or un-colored plastics material is required,e.g. for mineral water bottles. In another embodiment, the additiveand/or selected inorganic material may have uneven or slanted absorptioncharacteristics across the visible region of the spectrum possessingsignificant absorption minima or maxima. This may be desirable for theproduction of colored bottles. An additive which may impart a blue colorto a polymeric material, for example a plaque or preform may beespecially desirable as it can act not only to improve the reheatprofile of the polymeric material, but also to color the resultingplastics material. Polymers, particularly polyesters such aspoly(ethylene terephthalate), are known to yellow upon exposure toelevated temperatures. Indeed poly(ethylene terephthalate) yellows as itis being manufactured. In some cases, a toner may be added to thepolyester to adjust its color from a yellow back to a neutral shade.These toners are thus usually colorants that impart a blue shade, atypical example being cobalt acetate. Therefore, additives and/orinorganic materials which impart a blue shade to a polymeric material,for example plaque or perform, may also make good toners and may beespecially desirable. However, additives and/or inorganic materialswhich give rise to other visual colors can also be used as when used inconjunction with a complimentary colored toning agent, usually atraditional colorant, a neutral shade can easily be achieved.

Preferred inorganic materials may have absorption/absorptivitycharacteristics as described in any statement herein and, additionally,may have an absorption at 475 nm which is less than the absorption at700 nm. The absorption at 475 nm is preferably less than the absorptionat both 600 nm and 700 nm. The absorption at 475 nm is more preferablyless than the absorption at each of 550 nm, 600 nm and 700 nm. Theabsorption at 475 nm is most preferably less than the absorption at eachof 400 nm, 550 nm, 600 nm and 700 nm.

A particularly preferred inorganic aterial for use as described hereincomprises titanium nitride. Advantageously, this imparts a blue colorhaving an absorption minimum in the visible region around 475 nm.

A reheat additive as described herein may be produced from a number ofinorganic materials. Said reheat additive and/or said inorganic materialdescribed herein may be selected from one or more of the following groupof materials: elemental metals, metalloids, oxides, doped oxides, mixedoxides, nitrides, silicides or boride compounds. Preferably, said reheatadditive and/or said inorganic material is selected from one or more ofthe following group of materials: titanium nitride, zirconium nitride,indium tin oxide, reduced indium tin oxide, antimony tin oxide, gold,silver, molybdenum or tantalum.

A composition and/or reheat additive described herein may furthercomprise one or more additional materials to assist reheatcharacteristics of the polymeric materials. Additionally or alternately,a composition and/or additive may further comprise one or moreadditional materials to influence the characteristics of a polymericmaterial. For example, one or more black or grey body infrared absorbingmaterials may be incorporated with the additive which can result in theabsorption of more near-infrared radiation greater than 700 nm. Suchblack body or grey body infrared absorbing material may comprise blackcarbon, iron oxides, copper chromite or metallic antimony formed by thereduction of antimony trioxide during the polymerisation reaction. Othermaterials may include colorants etc. A composition and/or reheatadditive may be used in conjunction with organic materials, such asnear-infrared dyes, which have an absorption maximum in the region 700to 1400 nm.

Whilst the test referred to in accordance with the second aspect isconveniently undertaken a polyethylene terephthalate plaque, inorganicmaterials which pass the test may be incorporated into any type ofpolymeric material for improving its reheat characteristics, for examplewhen infra red lamps are used.

The polymeric material can essentially be any polymer which is used toproduce a plastics material, but preferably, the polymer comprises athermoplastic polymer (including both polymers which are synthetic ornatural). Preferred thermoplastic polymers are ones usable/used forinjection molding of articles such as container preforms and the like.Preferably, the thermoplastic polymer is selected from one or more ofthe following groups of polymers: polyesters, polycarbonates,polyamides, polyolefins, polystyrenes, vinyl polymers, acrylic polymersand copolymers and blends thereof. Preferred polymers are polyesters,polypropylene and oriented polypropylene which may suitably be used toproduce containers. Especially preferred polymers are polyesters as usedto make liquid containers and particularly beverage bottles such aspoly(ethylene terephthalate) or a copolymer thereof. A compositioncomprising a polymer with an additive and/or a said inorganic materialas described can be used in producing preforms such as containerpreforms before the preforms are heated or inserted into a stretch-blowmolding machine.

Polyethylene terephthalate used for injection molding purposes istypically post-condensed and has a molecular weight in the region ofabout 25,000 to 30,000. However, it has also been proposed to use afibre grade polyethylene terephthalate which is cheaper but isnon-post-condensed, with a lower molecular weight in the region of about20,000. It has further been suggested to use copolyesters ofpolyethylene terephthalate which contain repeat units from at least 85mole % terephthalic acid and at least 85 mole % of ethylene glycol.Dicarboxylic acids which can be included, along with terephthalic acid,are exemplified by phthalic acid, isophthalic acid,naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid,cyclohexanediacetic acid, diphenyl-4,4′-dicarboxylic acid, succinicacid, glutaric acid, adipic acid, azelaic acid and sebacic acid. Otherdiols which may be incorporated in the copolyesters, in addition toethylene glycol, include diethylene glycol, triethylene glycol,1,4-cyclohexanedimethanol, propane-1,3-diol, butane-1,4-diol,pentane-1,5-diol, hexane-1,6-diol, 3-ethylpentane-2,4-diol, 2-methylpentane 1,4-diol, 2,2,4-trimethylpentane-1,3-diol,2-ethylhexane-1,3-diol, 2,2-diethylpropane-1,3-diol, hexane-1,3-diol,1,4-di(hydroxyethoxy)-benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane,2,4-dihydroxy-1,1,3,3-tetramethyl-cyclobutane,2,2-bis-(3-hydroxyethoxyphenyl)-propane, and2,2-bis-(4-hydroxypropoxyphenyl)-propane. In this specification the term“polyethylene terephthalate” includes not only polyethyleneterephthalate but also such copolyesters.

Injection molding of polyethylene terephthalate and other polyestermolding compositions is typically carried out using an injection moldingmachine and a maximum barrel temperature in the range of from about 260°C. to about 285° C. or more, for example, up to about 310° C. The dwelltime at this maxim temperature is typically in the range of from about15 seconds to about 5 minutes or more, preferably from about 30 secondsto about 2 minutes.

In a preferred embodiment of the present invention, the additive and/orinorganic material is capable of increasing the percentage of reheat perunit of lightness lost ratio compared to an equivalent preform made froma polymer containing a traditional black or grey body absorbing agentsuch as any form of black carbon or metallic antimony formed by thereduction of antimony trioxide.

In a method as described according to the fifth aspect, said inorganicmaterial is preferably other than black carbon, metallic antimony, ironoxide or copper chromite.

The method of the fifth aspect may utilize an additive and/or inorganicmaterial as herein described. Polymers containing the additive will beparticularly suited for use in injection molding of articles.Furthermore, the additive may be dispersed in a liquid. Should theadditive be dispersed in a liquid then the liquid can be applied to thepolymer at the polymerization stage or the injection molding stage. Suchan article could potentially be any article which can be injectionmolded. Preferably, the article is a preform that can then bestretch-blow molded into a liquid container such as beverage bottlesusing infrared heating lamps.

The invention extends to a product comprising a polymeric material andan inorganic material as described herein, for example in accordancewith the first second aspects.

Said product may include at least 0.01 ppm, suitably at least 0.1 ppm,preferably at least 1 ppm, more preferably at least 2 ppm, even morepreferably at least 3 ppm, especially at least 4 ppm, based on theweight of said polymeric material in said product. Suitably, saidproduct includes less than 1000 ppm, preferably less than 500 ppm ofsaid inorganic material based on the weight of said polymeric material.

In said product, the ratio of the weight of polymeric material to theweight of said inorganic material is suitably in the range 10³ to 10⁶preferably in the range 2×10³ to 2.5×10⁵.

The product may be in the form of pellets or granules.

The product may be a molded article. In this case, it may be a perform,for example for a container and/or a container per se. A preferredcontainer is a bottle.

The invention extends to a method of making a product, the methodcomprising heating a composition comprising a polymeric material and aninorganic material as described herein, for example in accordance withthe first or second aspects, and forming the composition into a shape todefine the product.

The method may include an injection molding process, for example to makecontainer performs.

In the method of making said product, the composition is preferablyheated using an infra red source, for example one or more infra redheating lamps.

In accordance with a further aspect of the present invention, there isprovided an article made from a polymer containing an additive ofinorganic material which intrinsically exhibits greater absorptivitybetween 700 and 1400 nm than between 400 and 700 nm. In yet anotheraspect of the present invention, there is provided an article made froma polymer containing the additive of inorganic material that has agreater absorption maximum in the region between 700 to 1400 nm than theaverage absorption between 400 and 700 nm. A particularly preferredarticle may be a container preform. An especially preferred containerpreform is one which can be heated with infrared heating lamps prior tobeing stretch-blow molded into a liquid container such as a beveragebottle. The types of beverage such bottle can contain includes but isnot limited to beer, fruit juice, carbonated and still mineral water andother carbonated soft drinks.

In accordance with yet a further aspect of the present invention, thereis provided a method of increasing the reheat characteristics of apolymer, comprising the incorporation into the polymer particles of atleast one inorganic material, such that the polymer has a greater %reheat per unit of lightness lost ratio than an equivalent polymercontaining a traditional black or grey body absorbing agent such asblack carbon or metallic antimony formed by the reduction of antimonytrioxide or iron oxide or copper chromite.

An additional aspect of the present invention provides for the use of aninorganic material (not being black carbon, a metallic antimony, ironoxide or copper chromite) to improve the reheat properties of a polymeror polymeric composition.

In yet a further aspect of the present invention, there is provided amolded article formed from a polymer or polymeric composition mixed withan inorganic additive (not being black carbon, metallic antimony, ironoxide or copper chromite).

In a number of the aspects of the invention, the inorganicmaterial/additive may be selected from one or more of the followinggroup of materials: titanium nitride, zirconium nitride, indium tinoxide, reduced indium tin oxide, antimony tin oxide, gold, silver,molybdenum or tantalum. The inorganic material/additive is preferably ananoparticle having an average particle size less than 1 micron.Preferably, the average particle size of the inorganic material/additiveis 100 nm or less. The polymer or polymeric composition is preferablyselected from one or more of the following group of polymers:polyesters, polycarbonates, polyamides, polyolefins, polystyrenes, vinylpolymers, acrylic polymers and copolymers and blends thereof. Thearticle produced from a polymer comprising the polymer and inorganicmaterial/additive is preferably injection molded. Where the article is acontainer perform, said preform is preferably used in a stretch-blowmolding process requiring a heating step with infrared heating lamps, toproduce bottles suitable for use in containing liquids such asbeverages.

The invention will now be illustrated by way of example only withreference to the figures and the following examples, in which:

FIG. 1 illustrates the effect that an additive has on a polymer by meansof transmission spectrum. The Figure shows 60 nm particles of titaniumnitride (TiN) in PET, and for comparison the transmission spectrum forthe commercially available reheat polymer CB11e (Voridian) whichcontains a prior art infrared absorbing additive. Also shown is thetransmission spectrum of a PET polymer (9921W) which does not contain aninfrared-absorbing reheat additive.

FIG. 2 shows the transmission spectrum for an additive comprising 40 nmparticles of reduced indium tin oxide. Such a material exhibits greaterabsorptivity in the infrared compared to the visible spectrum.

FIG. 3 illustrates the spectral energy distribution of Philips IRKhalogen infrared heating lamps.

EXAMPLES

Preforms were made using a 160-ton HUSKY injection molding machine whichmade two preforms per shot. Each preform weighed approximately 34 gramsand was cylindrical, approximately 130 mm in length with a screw topbase. These preforms could be blown into one-liter bottles with apetaloid base.

Polyester injection molding took place at 270° C. General purposepoly(styrene) injection molding took place at 200° C.

The polymers used were:

-   -   B60 (DuPontSA)—a commercial, bottle grade resin PET resin, toned        and non-reheat.    -   Untoned B60 (DuPontSA) the same as B60 but without any toning        therefore showing the natural yellow color of the resin.    -   9921W (Voridian)—a commercial, bottle grade resin PET resin,        toned and non-reheat.    -   Laser+ (DuPontSA)—a commercial bottle grade reheat resin.    -   CB11e (Voridian)—a commercial bottle grade reheat resin.    -   General purpose poly(styrene) (GPS).

CB11e and Laser+ are both reheat resins containing metallic antimony asthe reheat aid. CB11e has approximately twice the reheat but hasapproximately twice the reduction in lightness as Laser+.

Where the inorganic particle compound was milled milling took place asfollows: The inorganic particle compound (5 g) was stirred into an oilknown to those skilled in the art to be compatible with the polymer theinorganic particles are to be incorporated into (total mass of oil andparticle mixture=50 g). The oil and particle mixture was thentransferred to a 100 ml glass jar approximately 55% filled with smallglass beads (1.2 mm diameter). The glass jar as shaken at 600 shakes perminute on a Red-Devil paint shaker. The milled dispersion was usedimmediately.

The following inorganic particle compounds were used as reheat aids.

-   -   1. Titanium nitride, average primary particle size 60 nm and 30        nm, supplied by Neomat of Riga, Latvia.    -   2. Reduced indium tin oxide, average primary particle size less        than 40 nm, was supplied by NanoProducts Corp. Longmont, Co.,        USA.    -   3. Antimony tin oxide, average primary article size of 30 nm was        supplied by NanoPhase Technologies, Romeoville, Ill., USA.    -   4. Lanthanum hexaboride nanopowder, average primary particle        size less than 40 nm, was supplied by NanoProducts Corp.        Longmont Co., USA.    -   5. Cobalt silicide (CoSi₂) powder of average particle size 1000        nm was supplied by Alfa-Aesar.

The near infrared dye employed was supplied by ADS Dyes, Toronto,Canada. The Lamp Black 101 (carbon black) was supplied by Degussa.Sigma-Aldrich supplied all other materials.

The particles of inorganic materials were mixed into the pre-madepolymer pellets by placing the powder or liquid dispersion of particlesof inorganic material into a bucket fitted with a lid containing thehot, dried polymer pellets and then shaking the bucket by hand to mixthe two together. The polymer pellets and particles of inorganicmaterial mixture were then immediately used to make preforms by aninjection molding process.

1. Preforms Example 1

TiN milled 60 nm at 25 ppm in B60 resin.

Example 1a

TiN milled 60 nm at 25 ppm in 9921W resin.

Example 1b

TiN milled 30 nm at 25 ppm in 9921W resin.

Example 2

TiN milled at 5 ppm in untoned B60 resin.

Example 3

TiN milled at 10 ppm in untoned B60 resin.

Example 4

LaB₆ powder at 100 ppm in B60 resin.

Example 5

LaB₆ milled at 100 ppm in B60 resin.

Example 6

ITO powder at 100 ppm in B60 resin.

Example 6a

ITO powder at 100 ppm in 9921W resin.

Example 7

ITO milled resin at 100 ppm in 860 resin.

Example 8

ATO powder at 463 ppm in B60 resin.

Example 9

ATO milled at 100 ppm in B60 resin.

Example 10

TiN milled at 10 ppm and ITO milled at 10 ppm in untoned B60 resin.

Example 11

TiN milled at 10 ppm and near-infrared organic dye at 50 ppm in untoned860 resin.

Example 12

TiN milled at 10 pm and tantalum nanopowder at 100 ppm in untoned 860.

Example 13

TiN milled at 5 ppm and ITO milled at 75 ppm in untoned B60 resin.

Example 14

TiN milled at 10 ppm and ITO milled at 50 ppm in untoned 1360 resin.

Example 15

Mo nanosized powder at 250 ppm into B60 resin.

Example 16

Cobalt silicide at 100 ppm into B60 resin.

Example 17

ITO milled at 100 ppm in GPS.

Example 18

TiN milled at 25 ppm in GPS.

The colors of the preforms were measured using a Minolta cm-3700dspectrophotometer (D₆₅ illumination, 10° observer, specular included, UVincluded) linked to an IBM compatible PC.

The preform reheat tests were performed by measuring the roomtemperature-temperature of a preform using a Raytek MiniTemp laserdigital infrared thermometer and then placing it into a stretchblow-molding bottle machine with a single preform fitting, with all ninePhilips IRK halogen infrared heating lamps set to 75% power. Thepreforms were heated for 35 seconds after which time the temperature ofthe preform was recorded. The spectral energy distribution of the lampsfitted into this machine is displayed in FIG. 3. The temperaturedifference (temperature after 35 seconds of heating minus the roomtemperature-temperature of the preform) was then used to calculate %change in reheat relative to non-reheat control (either B60 or untonedB60).

Example 19

Formulation of inorganic particles in ethylene glycol suitable foradding directly to a polyester polymerization reaction.

Reduced indium tin oxide (5 g) or titanium nitride (5 g) was stirredinto ethylene glycol (up to 50 g) and added to a glass jar 50% filledwith small glass milling beads (˜1.2 mm in diameter). The jar was samplewas milled by shaking it on the Red-Devil paint shaker at 600 s.p.m. for10 minutes. The sample was then ready for adding directly to a polyesterpolymerization reaction mixture.

Results

1. Preform Colors

L a b C h° B60 78.96 −0.69 1.61 1.75 113.3 Untoned B60 80.82 −0.47 3.253.28 98.2 9921W 77.19 −0.89 4.52 4.6 101.2 Laser+ 70.25 −0.27 0.84 0.88107.6 CB11e 60.54 −0.96 2.66 2.83 109.9 Example 1 64.03 −3.33 −4.10 5.29230.9 Example 1a 63.12 −2.89 −3.87 5.01 215.3 Example 1b 54.47 −4.51−7.20 8.50 237.9 Example 2 77.40 −1.15 0.96 1.50 140.2 Example 3 73.62−1.89 −0.37 1.93 191.0 Example 4 70.64 −0.46 7.33 7.34 93.6 Example 567.88 −1.67 6.69 6.89 104.1 Example 6 76.63 −0.60 6.56 6.59 95.2 Example6a 74.89 −0.59 8.35 8.37 94.0 Example 7 76.46 −0.67 8.82 8.84 94.4Example 8 63.83 0.95 14.3 14.3 86.2 Example 9 75.85 −0.78 6.76 6.8096.55 Example 10 73.66 −1.86 0.07 1.86 117.9 Example 11 69.78 −5.0213.51 14.4 110.4 Example 12 66.48 −1.34 0.50 1.43 159.4 Example 13 74.32−1.22 5.57 5.70 102.3 Example 14 72.44 −1.84 1.74 2.54 136.7 Example 1566.22 −0.57 1.10 1.24 117.3 Example 16 76.08 −1.08 3.20 3.38 108.7 GPS85.50 −0.08 0.68 0.68 96.92 Example 17 83.43 −0.20 4.31 4.31 92.7Example 18 71.62 −2.03 −5.22 5.60 248.7

2. Reheat Versus Lightness

% Reheat/Unit of % Reheat lightness lost B60 0 0 Untoned B60 0 0 9921W 00 GPS 0 0 Laser+ 7.5 0.80 CB11e 17.0 0.92 Example 1 16.8 1.05 Example 1a16.9 1.20 Example 1b 22.3 0.91 Example 2 18.0 0.99 Example 3 5.4 0.74Example 4 14.0 0.61 Example 5 15 1.35 Example 6 16.9 6.76 Example 6a17.0 7.39 Example 7 18.1 7.24 Example 8 17.9 1.18 Example 9 2.0 0.64Example 10 9.6 1.32 Example 11 10.3 0.92 Example 12 11.2 0.78 Example 1317.1 2.71 Example 14 16.9 2.13 Example 15 16.5 1.30 Example 16 5.7 1.11Example 17 18.2 8.79 Example 18 12.7 0.91

In every case the inorganic material reheat aid system has been able toincrease the % reheat of the control resin it was incorporated into andas heating was for a fixed time of 35 seconds thus the rate of reheatwas increased. Indeed in several instances not only was there anincrease in reheat over the control but the % reheat per unit oflightness lost ratio was higher than the preforms made from both of thetwo commercial reheat resins. This gave rise to preforms with the samereheat as the two commercial reheat standard but a higher lightnessvalue thus making them desirable for use by the mineral water bottleindustry.

Example 20

Type One Inorganic Materials—Absorptivity Determination

Absorptivity was determined by measuring the absorbance of plaquescontaining the particles of inorganic material as follows.

Plaques were prepared using a 22-ton BOY injection molding machine thatproduces plaques measuring 75×50 mm, of two thicknesses, 2 and 2.5 mm.

Plaques were prepared comprising 9921W containing reduced indium tinoxide (powder) at 100 ppm. Control, CB11e and Laser+plaques were alsoprepared.

The spectrum of the plaques in the region 300 to 1100 nm was measuredusing a Perkin-Elmer Lambda 35 uv-vis spectrophotometer linked to an IBMcompatible PC.

Absorptivity was then calculated by determining the % change in measuredabsorbance that occurs across the visible region 400 to 700 nm, and thenin the near infrared region 700 to 1100 nm. This was perform as follows:((Abs_(λ2)−Abs_(λ1))/Abs_(λ1))*100

Where Abs 1 and 2 are the absorption at either 400, 700 or 1100 nm with_(λ)2 always being greater than _(λ)1, i.e. when _(λ)1=400 nm then_(λ)2=700 nm and when _(λ)1=700 nm then _(λ)2=1100 nm.

Absorptivity % _(400 to 700 nm) Absorptivity % _(700 to 1100 nm) 9921W−67 −13 Laser+ −33 0.00 CB11e −35 −1 ITO −72 +45

Example 21

Type Two Inorganic Materials—Absorbance Measurement

A plaque of 9921W was prepared containing TiN (30 nm at 15 ppm) asabove.

The plaques were used to generate spectrophotometer data. The averageabsorbance over the range 400 to 700 nm and the maximum absorbance inthe range 700 to 1100 nm was determined. The % difference between thetwo was calculated.

700-1100 max 400-700 ave diff. % diff 9921W 0.0661 0.103031 −0.03693 −35Laser+ 0.1202 0.137931 −0.01773 −13 CB11e 0.1877 0.212215 −0.02452 −12TiN 0.2463 0.228938 0.17362 +8

Examples 22 to 24

2.5 mm thick plaques were made from a composition comprising a selectedinorganic material as an additive incorporated into a polymer andcompared to plaques of the same dimensions made from the same polymerwithout the selected inorganic material and with no other materialdifferences other than the lack of the additive. If the additive isincorporated during polymerisation, the comparison is made to a polymermade with the same recipe and polymerised under the same conditions butwithout the additive.

The plaques were then assessed using a Varian Cary 500 UV-VIS-NIRspectrophotometer and the % transmission at wavelengths between 400 nmand 550 nm; 700 nm and 1100 nm; and 700 to 1600 nm was recorded. Thesefigures were then converted into absorbance by the equationAbsorbance=−Log 10 (transmission %/100).

The absorbance of the additive (at each wavelength) was obtained bysubtracting the absorbance of polymer containing the additive from theabsorbance of the polymer without the additive.

The values for the maximum absorption between 400 nm and 550 nm(referred to hereinafter as ABS-1), for the maximum absorption between700 to 1100 nm (referred to hereinafter as ABS-2) and for the maximumabsorption between 700 to 1600 nm (referred to hereinafter as ABS-3)were determined by taking the maximum from each range. Then the ratiosABS-1/ABS-2; and ABS-1/ABS-3 were determined. Details on materialsassessed and results are provided in the table below.

Example Details on Ratio Ratio No. additive Resin ABS-1/ABS-2ABS-1/ABS-3 22 10 ppm TiN Untoned 0.42 0.42 (milled) B60 23 100 ppm9921W 1.00 0.74 ITO 24 25 ppm LaB₆ Untoned 0.54 0.54 B60

Additionally, plaques prepared as described in Example 19 were tested asdescribed for Examples 22 to 24 and found to perform in a similarmanner.

1. A container or a preform for a container, wherein said container orpreform comprises a composition which comprises a polymeric material andan inorganic material selected from indium tin oxide, reduced indium tinoxide and antimony tin oxide.
 2. A container or preform as claimed inclaim 1, which includes at least 0.01 ppm and less than 1000 ppm of saidinorganic material based on the weight of said polymeric material.
 3. Acontainer or preform as claimed in claim 1, wherein at least 90% of saidinorganic material comprises particles having a maximum dimension whichis less than 10 microns.
 4. A container or preform as claimed in claim1, wherein the inorganic material is colloidal or nanoparticulatematter.
 5. A container or preform as claimed in claim 1, wherein thepolymeric material is selected from one or more of the followingpolymers: polyesters, polycarbonates, polyamides, polyolefins,polystyrenes, vinyl polymers, acrylic polymers and copolymers and blendsthereof.
 6. A container or preform as claimed in claim 1, wherein saidpolymeric material comprises poly(ethylene terephthalate).
 7. Acontainer or preform as claimed in claim 1, wherein said container isstretch blow moulded.
 8. A method of making a container, the methodcomprising: (a) selecting a preform for a container wherein said preformcomprises a composition which comprises a polymeric material and aninorganic material selected from indium tin oxide, reduced indium tinoxide and antimony tin oxide; and (b) heating the selected preform andforming it into a container.
 9. A method as claimed in claim 8, wherein,in said method, the composition is heated using an infrared source. 10.A method of improving the reheat characteristics of a polymericmaterial, the method comprising contacting the polymeric material orcontacting one or more monomers or oligomers or prepolymers arranged tobe polymerised to prepare the polymeric material with an inorganicmaterial selected from indium tin oxide, reduced indium tin oxide andantimony tin oxide, wherein said inorganic material is dispersed in thepolymeric material and said polymeric material includes at least 0.01ppm and less than 1,000 ppm of said inorganic material based on theweight of said polymeric material.
 11. A method according to claim 10,wherein granules or pellets which comprise the polymeric material andinorganic material are prepared.
 12. A method according to claim 10,wherein said polymeric material comprises poly(ethylene terephthalate).13. A method according to claim 10, wherein at least 90% of saidinorganic material comprises particles having a maximum dimension whichis less than 10 microns.
 14. A composition with improved reheatcharacteristics, said composition comprising a polymeric material and aninorganic material dispersed in the polymeric material, wherein saidcomposition includes at least 0.01 ppm and less than 1,000 ppm of saidinorganic material based on the weight of said polymeric material; andwherein said inorganic material is selected from indium tin oxide,reduced indium tin oxide and antimony tin oxide.
 15. A compositionaccording to claim 14, wherein said polymeric material comprisespoly(ethylene terephthalate).
 16. A composition according to claim 14,wherein the inorganic material is colloidal or nanoparticulate matter.17. A method of improving the reheat characteristics of a polymericmaterial, the method comprising contacting the polymeric material orcontacting one or more monomers or oligomers or prepolymers arranged tobe polymerised to prepare the polymeric material with an inorganicmaterial selected from indium tin oxide, reduced indium tin oxide andantimony tin oxide, wherein granules or pellets which comprise thepolymeric material and inorganic material are prepared.